Protein detoxification is the process by which proteins containing methylated arginine are broken down and removed from the body. Arginine (Arg) is a non-essential amino acid and one of the most commonly occurring natural amino acids. Methylated arginine is a modified version of arginine that is commonly formed from protein arginine (arginine incorporated in protein). Asymmetrically methylated forms of arginine are toxic when released during protein turnover.The protein detoxification pathway eliminates free methylated-arginine derivatives from the cell. Symmetrically methylated forms are not toxic and are excreted unchanged by the kidney. Asymmetrically methylated forms however are toxic and must first be broken down. This step requires the enzyme dimethylarginine dimethylaminohydrolase (